1. Field of the Invention
The present invention relates in general to door locks, and more particularly to automotive slide door locks of a type which comprise a latch plate engageable with a striker to achieve a latched condition of the slide door and a pawl member engageable with the latch plate to keep the latched condition of the slide door. More specifically, the present invention is concerned with a door lock used as an auxiliary door lock in a slide door dual lock system which employs two door locks to latch the slide door to a door opening.
2. Description of the Prior Art
Among various locks for automotive slide doors, there is a dual lock system which includes main and auxiliary door locks which are mounted to rear and front portions of the slide door. Upon closing of the slide door, the main and auxiliary door locks latch the rear and front portions of the door to the vehicle body. Usually, the front or auxiliary door lock is employed for tightly restraining the latched door even upon a vehicle collision. For the functions of these two door locks, a door opening of the vehicle body is equipped with rear and front strikers to which respective latch plates of the main and auxiliary door locks are engageable.
Each of the main and auxiliary door locks is constructed to have three conditions, which are a full-latch condition wherein the latch plate fully latches the striker with an aid of pawl member to completely latch the door at the closed position, a half-latch condition wherein the latch plate incompletely latches the striker with an aid of the pawl member to incompletely latch the door at the closed position and an open condition wherein the latch plate is released from the pawl member to release the striker thereby to release the door.
In case of an auto-slide door wherein initial opening motion and subsequent opening movement of the door are carried out by an electric power, an electric actuator is used for actuating both the main and auxiliary door locks. In this case, a link member is used which extends from the electric actuator to both the main and auxiliary door locks. When, for the purpose of opening the slide door, an operator (or driver) operates a so-called "open switch" ON, the electric actuator is energized to move the link member in a direction to cancel the latched condition of the latch plate of each door lock. Usually, the link member is connected to both the inside and outside door handles, so that the two door locks can be actuated by the door handles.
Due to the nature of the slide door, when the door is slid into the door opening, the latching action of the auxiliary door lock to the front striker is completed before that of the main door lock to the rear striker. That is, when the slide door is about to be led into the door opening, the door is inclined relative to the door opening having the front or auxiliary door lock positioned close to the front striker and the rear or main door lock positioned away from the rear striker. Thus, further movement of the slide door into the door opening induces firstly the engagement of the auxiliary door lock with the front striker and then the engagement of the main door lock with the rear striker. In fact, until the main door lock completes its full-latch condition, the auxiliary door lock is compelled to assume a so-called "over-stroke condition" wherein the latch plate is overly turned beyond its full-latch position. When the slide door is finally and thus neatly put into the door opening, the auxiliary door lock is turned back to the normal full-latch condition. That is, due to the nature of the slide door, the two door locks are compelled to operate with different timings.
Such different timing operation of the two door locks tends to induce the following disadvantage at the time of opening the slide door.
That is, when, due to ON turning of the open switch, the electric actuator is energized to move the link member in the latch canceling direction, the latch plates of both the main and auxiliary door locks are released from respective pawl members and the main door lock is instantly turned to its open condition. However, the auxiliary door lock can not be turned to its open condition until the slide door makes a certain open motion from the closed position. That is, during this time, the auxiliary door lock is kept in the above-mentioned "over-stroke condition". This means that it is necessary to keep the electric actuator energized for a certain time even after completion of turning of the main door lock to its open position. If the energization is stopped just after turning of the main door lock to the open position, the auxiliary door lock is turned back to its full-latch (or half-latch) condition. Of course, in this case, the slide door can not be opened. In practice, in order to suppress this undesired phenomenon, an elongate electric connector unit has been hitherto employed for keeping the electric connection between the electric actuator installed in the slide door and a power source installed in the vehicle body.